Scale NSString Font to UIImage Size - xcode

Question

I'm writing text onto a image taken from the iDevice's camera or chosen from the photo library but I need the fontsize scaled according to width/height of the image. Here's my current code:
UIGraphicsBeginImageContext(img.size);
CGRect aRectangle = CGRectMake(0,0, img.size.width, img.size.height);
[img drawInRect:aRectangle];
[[UIColor whiteColor] set]; // set text color
NSInteger fontSize = 45;
UIFont *font = [UIFont systemFontOfSize:fontSize];// set text font
[ text drawInRect : aRectangle // render the text
withFont : font
lineBreakMode : UILineBreakModeTailTruncation // clip overflow from end of last line
alignment : UITextAlignmentCenter ];
UIImage *theImage=UIGraphicsGetImageFromCurrentImageContext(); // extract the image
UIGraphicsEndImageContext(); // clean up the context.
return theImage;</i>

Answer 1

You want something like this. It creates a rect half the size of your image, then uses a binary search to zoom in on the font size you want.
//---- initial data
CGSize szMax = CGSizeMake(<imgWidth> / 2, <imgHeight> / 2);
CGFloat fMin = 2; //-- the smallest size font we want
CGFloat fMax = 100; //-- the largest size font we want
CGFloat fMid; //-- the middle of min and max
while ((fMax - fMin) >= 1.0) //-- repeat until the sizes converge
{
fMid = (fMin + fMax) / 2.0; //-- compute mid-point
UIFont *pfnt = [UIFont systemFontOfSize: fMid]; //-- create middle-sized font
//---- compute the size of the text using the mid-sized font
CGSize szStr = [pStr sizeWithFont: pfnt constrainedToSize: szMax lineBreakMode: UILineBreakModeWordWrap];
if (szStr.height > szMax.height)
fMax = fMid; //-- text too tall, set max to mid-point
else
fMin = fMid; //-- text too short, set min to mid-point
}
//---- 'fMid' is the size you want.